'''
Created on 2011-5-22

@author: tie
'''

#f(0)=0,f(1)=1
#f(n)=f(n-1)+f(n-2)

n=10
f1=0
f2=1
fn=0
for i in range(2,n+1):
    fn=f1+f2
    f1=f2
    f2=fn
print(fn)
    